In Ashton v. Kentucky, the U.S. Supreme Court ruled in 1966 that a state cannot constitutionally apply its criminal libel laws to punish the publication of statements about public officials unless it can be proven that such statements were made with actual malice - knowledge of their falsity or reckless disregard for whether they are true or false. The case involved three Louisville residents who published an article criticizing local law enforcement and were subsequently convicted under Kentucky's criminal libel statute. In a unanimous decision, the court overturned these convictions, extending the constitutional protections established in New York Times Co. v Sullivan (1964) to cover criticisms not just of public figures but also government operations more broadly.

In the dissenting opinion for Ashton v. Kentucky, Justice Harlan argued that the majority's decision was a departure from established legal principles regarding libel law and freedom of speech. He contended that historically, states have been allowed to define their own standards for what constitutes libelous speech, as long as they do not infringe upon constitutionally protected expression. The majority's ruling effectively stripped states of this power by imposing an overly broad definition of "public official" and requiring proof of actual malice in all cases involving public figures. This shift would make it significantly more difficult for individuals to seek redress when defamed by false statements made with reckless disregard for the truth. Furthermore, he expressed concern about potential chilling effects on free speech if people fear being sued under these new stringent standards.